1. Field of the Invention
The present invention relates to a photographic film cartridge, a lens-fitted film unit for use therewith, and an assembling/disassembling method for the film unit. More particularly, the present invention relates to a lens-fitted film unit loaded with a film cartridge having a shell formed of resin, and a film unit assembling/disassembling method.
2. Description of Related Art
A conventional 135-type photographic film cartridge includes a cartridge shell which is constituted of a tube formed from a thin metal plate and a pair of end caps. A photographic film (hereinafter referred to as film) is wound on a spool formed from resin. The spool is rotatably mounted in the cartridge shell. A film passage port is formed in the cartridge shell. Light-blocking ribbons are attached to the inside of the passage port, so as to prevent ambient light from entering into the cartridge shell through the passage port. It is regarded as desirable nowadays to be able to recycle the parts of the cartridge after use, because discarded waste of industrial products damages the environment. The conventional cartridge having a metal shell is disadvantageous, because the spool of the cartridge is resinous and must be treated differently from the shell. Recycling of the conventional cartridge therefore requires disassembly of the shell and classification of the parts, and is characterized by conspicuously low efficiency in practice.
There is a proposal to form a cartridge shell from resin similar to that of the spool, and of using an openable cover member for preventing ambient light from entering into the cartridge shell through the passage port.
Lens-fitted film units (hereinafter referred to simply as film units) are now on the market, e.g. under the trade name "Fujicolor Quick Snap" (manufactured by Fuji Photo Film Co., Ltd.) Such known film units are a single-use camera preloaded with photographic film. The film unit has a main body provided with a film supply chamber and a cartridge chamber formed on opposite horizontal sides of a taking lens. The unexposed film is wound in a roll in the film supply chamber. An externally rotatable winding wheel is coupled with a spool in the conventional cartridge contained in the cartridge chamber. A user who has purchased the film unit winds the film frame by frame back into the cartridge after each exposure. The film unit in its entirety is forwarded to a photo laboratory after exposure of the film. An operator at the laboratory unloads the film, and handles it for development and printing. It is possible for the operator to remove the cartridge from the film unit in a lighted room, because the cartridge has the ribbons which keep out ambient light incident on the passage port.
However, the passage port, through which the cartridge is openable by use of the cover member as described above, is apt to admit ambient light into the cartridge shell and would expose the film in the cartridge to light even after photography. The known cartridge having a resinous shell has such a disadvantage, even though better for recycling. The exposed film is withdrawn from the cartridge which has been unloaded from the film unit. Prior to withdrawing the exposed film from the cartridge, the cover member of a cartridge processed in a lighted room must be kept tightly closed by external operation. If the exposed film is handled in a darkroom all before withdrawal from the cartridge, this causes problems of low efficiency and inconsistency of processing of films from a number of different cartridges.